Epoxide hydrolases are a group of enzymes ubiquitous in nature, detected in species ranging from plants to mammals. These enzymes are functionally related in that they all catalyze the addition of water to an epoxide, resulting in a diol. Epoxide hydrolases are important metabolizing enzymes in living systems. Epoxides are reactive species and once formed are capable of undergoing nucleophilic addition. Epoxides are frequently found as intermediates in the metabolic pathway of xenobiotics. Thus in the process of metabolism of xenobiotics, reactive species are formed which are capable of undergoing addition to biological nucleophiles. Epoxide hydrolases are therefore important enzymes for the detoxification of epoxides by conversion to their corresponding, non-reactive diols.
In mammals, several types of epoxide hydrolases have been characterized including soluble epoxide hydrolase (sEH), also referred to as cytosolic epoxide hydrolase, cholesterol epoxide hydrolase, LTA4 hydrolase, hepoxilin hydrolase, and microsomal epoxide hydrolase (Fretland and Omiecinski, Chemico-Biological Interactions, 129: 41-59 (2000)). Epoxide hydrolases have been found in all tissues examined in vertebrates including heart, kidney and liver (Vogel, et al., Eur J. Biochemistry, 126: 425-431 (1982); Schladt et al., Biochem. Pharmacol., 35: 3309-3316 (1986)). Epoxide hydrolases have also been detected in human blood components including lymphocytes (e.g. T-lymphocytes), monocytes, erythrocytes, platelets and plasma. In the blood, most of the sEH detected was present in lymphocytes (Seidegard et al., Cancer Research, 44: 3654-3660(1984)).
The epoxide hydrolases differ in their specificity towards epoxide substrates. For example, sEH is selective for aliphatic epoxides such as epoxide fatty acids while microsomal epoxide hydrolase (mEH) is more selective for cyclic and arene oxides. The primary known physiological substrates of sEH are four regioisomeric cis epoxides of arachidonic acid known as epoxyeicosatrienoic acids or EETs. These are 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acid. Also known to be substrates are epoxides of linoleic acid known as leukotoxin or isoleukotoxin. Both the EETs and the leukotoxins are generated by members of the cytochrome P450 monooxygenase family (Capdevila, et al., J. Lipid Res., 41: 163-181 (2000)).
The various EETs appear to function as chemical mediators that may act in both autocrine and paracrine roles. EETs appear to be able to function as endothelial derived hyperpolarizing factor (EDHF) in various vascular beds due to their ability to cause hyperpolarization of the membranes of vascular smooth muscle cells with resultant vasodilation (Weintraub, et al., Circ. Res., 81: 258-267 (1997)). EDHF is synthesized from arachidonic acid by various cytochrome P450 enzymes in endothelial cells proximal to vascular smooth muscle (Quilley, et al., Brit. Pharm., 54: 1059 (1997)); Quilley and McGiff, TIPS, 21: 121-124 (2000)); Fleming and Busse, Nephrol. Dial. Transplant, 13: 2721-2723 (1998)). In the vascular smooth muscle cells EETs provoke signaling pathways which lead to activation of BKCa2+ channels (big Ca2+ activated potassium channels) and inhibition of L-type Ca2+ channels. This results in hyperpolarization of membrane potential, inhibition of Ca2+ influx and relaxation (Li et al., Circ. Res., 85: 349-356 (1999)). Endothelium dependent vasodilation has been shown to be impaired in different forms of experimental hypertension as well as in human hypertension (Lind, et al., Blood Pressure, 9: 4-15 (2000)). Impaired endothelium dependent vasorelaxation is also a characteristic feature of the syndrome known as endothelial dysfunction (Goligorsky, et. al., Hypertension, 37[part 2 ]:744-748 ( 2001). Endothelial dysfunction plays a significant role in a large number of pathological conditions including type 1 and type 2 diabetes, insulin resistance syndrome, hypertension, atherosclerosis, coronary artery disease, angina, ischemia, ischemic stroke, Raynaud's disease and renal disease. Hence, it is likely that enhancement of EETs concentration would have a beneficial therapeutic effect in patients where endothelial dysfunction plays a causative role. Other effects of EETs that may influence hypertension involve effects on kidney function. Levels of various EETs and their hydrolysis products, the DHETs, increase significantly both in the kidneys of spontaneously hypertensive rats (SHR) (Yu, et al., Circ. Res. 87: 992-998 (2000)) and in women suffering from pregnancy induced hypertension (Catella, et al., Proc. Natl. Acad. Sci. U.S.A., 87: 5893-5897 (1990)). In the spontaneously hypertensive rat model, both cytochrome P450 and sEH activities were found to increase (Yu et al., Molecular Pharmacology, 2000, 57, 1011-1020). Addition of a known sEH inhibitor was shown to decrease the blood pressure to normal levels. Finally, male soluble epoxide hydrolase null mice exhibited a phenotype characterized by lower blood pressure than their wild-type counterparts (Sinal, et al., J.Biol.Chem., 275: 40504-40510 (2000)).
EETs, especially 11,12- EET, also have been shown to exhibit anti-inflammatory properties (Node, et al., Science, 285: 1276-1279 (1999); Campbell, TIPS, 21: 125-127 (2000); Zeldin and Liao, TIPS, 21: 127-128 (2000)). Node, et al. have demonstrated 11,12-EET decreases expression of cytokine induced endothelial cell adhesion molecules, especially VCAM-1. They further showed that EETs prevent leukocyte adhesion to the vascular wall and that the mechanism responsible involves inhibition of NF-κB and IκB kinase. Vascular inflammation plays a role in endothelial dysfunction (Kessler, et al., Circulation, 99: 1878-1884 (1999)). Hence, the ability of EETs to inhibit the NF-κB pathway should also help ameliorate this condition.
In addition to the physiological effect of some substrates of sEH (EETs, mentioned above), some diols, i.e. DHETs, produced by sEH may have potent biological effects. For example, sEH metabolism of epoxides produced from linoleic acid (leukotoxin and isoleukotoxin) produces leukotoxin and isoleukotoxin diols (Greene, et al., Arch. Biochem. Biophys. 376(2): 420-432 (2000)). These diols were shown to be toxic to cultured rat alveolar epithelial cells, increasing intracellular calcium levels, increasing intercellular junction permeability and promoting loss of epithelial integrity (Moghaddam et al., Nature Medicine, 3: 562-566 (1997)). Therefore these diols could contribute to the etiology of diseases such as adult respiratory distress syndrome where lung leukotoxin levels have been shown to be elevated (Ishizaki, et al., Pulm. Pharm.& Therap., 12: 145-155 (1999)). Hammock, et al. have disclosed the treatment of inflammatory diseases, in particular adult respiratory distress syndrome and other acute inflammatory conditions mediated by lipid metabolites, by the administration of inhibitors of epoxide hydrolase (WO 98/06261; U.S. Pat. No. 5,955,496).
A number of classes of sEH inhibitors have been identified. Among these are chalcone oxide derivatives (Miyamoto, et al. Arch. Biochem. Biophys., 254: 203-213 (1987)) and various trans-3-phenylglycidols (Dietze, et al., Biochem. Pharm. 42: 1163-1175 (1991); Dietze, et al., Comp.Biochem. Physiol. B, 104: 309-314 (1993)).
More recently, Hammock et al. have disclosed certain biologically stable inhibitors of sEH for the treatment of inflammatory diseases, for use in affinity separations of epoxide hydrolases and in agricultural applications (U.S. Pat. No. 6,150,415). The Hammock '415 patent also generally describes that the disclosed pharmacophores can be used to deliver a reactive functionality to the catalytic site, e.g., alkylating agents or Michael acceptors, and that these reactive functionalities can be used to deliver fluorescent or affinity labels to the enzyme active site for enzyme detection (col. 4, line 66 to col. 5, line 5). Certain urea and carbamate inhibitors of sEH have also been described in the literature (Morisseau et al., Proc. Natl. Acad. Sci., 96: 8849-8854 (1999); Argiriadi et al., J. Biol. Chem., 275 (20) 15265-15270 (2000); Nakagawa et al. Bioorg. Med. Chem., 8: 2663-2673 (2000)).
WO 99/62885 (A1) discloses 1-(4-aminophenyl)pyrazoles having anti-inflammatory activity resulting from their ability to inhibit IL-2 production in T-lymphocytes, it does not however, disclose or suggest compounds therein being effective inhibitors of sEH. WO 00/23060 discloses a method of treating immunological disorders mediated by T-lymphocytes by administration of an inhibitor of sEH. Several 1-(4-aminophenyl)pyrazoles are given as examples of inhibitors of sEH.
As outlined in the discussion above, inhibitors of sEH are useful therefore, in the treatment of cardiovascular diseases such as endothelial dysfunction either by preventing the degradation of sEH substrates that have beneficial effects or by preventing the formation of metabolites that have adverse effects. Further investigation by the present inventors has shown that the inhibition of IL-2 production and inhibition of sEH are separable activities with divergent structure-activity relationships. New embodiments of 1-(4-aminophenyl)pyrazoles, potent and selective for inhibition of sEH are disclosed herein.
All references cited above and throughout this application are incorporated herein by reference in their entirety.